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Reprint, June, 1916. 
UNITED STATES DEPARTMENT OF AGRICULTURE 
Contribution from the Bureau of Animal Industry 
A. D. MELVIN, Chief 
Washington, D.C. PROFESSIONAL PAPER January 8, 1916 
THE PRESENT STATUS OF THE PASTEURIZATION 
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OF MILK. 
By S. Henry Ayers, Bacteriologist, Dairy Division. 
CONTENTS. 
Page. Page. 
_ Meaning of the term ‘:pasteurization’’....... il sSupervasionm ofthe process:-ce.ce-.scneee eee 7 
Besivie Of PASLEUITIZATION....- 2... ccc cewecsnences 1} PHandline pasteurizedsmilikes ss... sees 8 
Extent of pasteurization in the United States. 3) [RX Costot pasteunizinesmilk=s tacos ss ne ts oe ee 9 
Methods of pasteurization................--- 4 | Bacteria which survive pasteurization....... 9 
Advantages of low-temperature pasteuriza- Modern theories of pasteurization............ 13 
HIGHS 5 6 BSS BERBOESSE AEE RE ees ee sce seh ae 5 | The necessity for pasteurization............. 15 
Temperature and methods most suitable for References tOliberavune sea. ece eee ee oer 16 
BASLCUTIZALION |< 55221 scl A TO en 6 
MEANING OF THE TERM “ PASTEURIZATION.” 
The term “pasteurization,” as applied to milk, should mean a 
process of heating to 145° F. and holding at that temperature for 30 
minutes, but as applied under commercial conditions it is the precess 
of heating for a short or long period, as the different methods de- 
mand, at temperatures usually between 140° and 185° F. The process 
is followed by rapid cooling. The term originated from the experi- 
ments of Louis Pasteur in France. From 1860 to 1864, in experiment- 
ing on the “diseases” of wine, he found that heating for a few 
moments at temperatures of from 122° to 140° F. was sufficient to pre- 
vent abnormal fermentations and souring in the wine. A little later 
he found that by a similar heating beer could be preserved from sour- 
ing. The application of the process gave rise to the term “ pasteuri- 
- zation.” 
VALUE OF PASTEURIZATION. 
From a sanitary standpoint the value of pasteurization is of the 
greatest importance when market milk 1s under consideration. The 
Notre.—This bulletin will be of interest to health officers, medical men, scientific dairy- 
men, and others who may be interested in the subject of pasteurization. 
47267°—16 
